Automated storage and retrieval system

ABSTRACT

An automated storage and retrieval system includes a track system having a first set of parallel tracks and a second set of parallel tracks. The first and second sets of tracks form a grid pattern of grid cells. Storage containers are arranged in storage columns located beneath the track system. Container handling vehicles lift and move storage containers. The container handling vehicles are configured to move laterally on the track system above the storage columns to access the storage containers via grid openings. Each container handling vehicle includes: a protruding section which extends horizontally beyond the footprint of the container handling vehicle and, when the container handling vehicle is positioned above a grid cell, into a neighbouring grid cell; and a recessed section arranged to accommodate the protruding sections of another container handling vehicle when operating over a neighbouring grid cell.

TECHNICAL FIELD

The present invention relates to an automated storage and retrievalsystem.

In particular, the present invention relates to an automated storage andretrieval system comprising:

-   -   a track system comprising a first set of parallel tracks        arranged in a horizontal plane and extending in a first        direction, and a second set of parallel tracks arranged in the        horizontal plane and extending in a second direction which is        orthogonal to the first direction, which first and second sets        of tracks form a grid pattern in the horizontal plane comprising        a plurality of adjacent grid cells, each comprising a grid        opening defined by a pair of adjacent tracks of the first set of        tracks and a pair of adjacent tracks of the second set of        tracks;    -   a plurality of stacks of storage containers arranged in storage        columns located beneath the track system, wherein each storage        column is located vertically below a grid opening;    -   a plurality of container handling vehicles for lifting and        moving storage containers stacked in the stacks, the container        handling vehicles being configured to move laterally on the        track system above the storage columns to access the storage        containers via the grid openings, wherein each of the plurality        of container handling vehicles comprises:        -   a wheel assembly for guiding the container handling vehicle            along the track system;    -   wherein the container handling vehicle has a footprint with a        horizontal extent which is equal to or less than the horizontal        extent of a grid cell.

The present invention also relates to a container handling vehicle forsuch an automated storage and retrieval system, the container handlingvehicle comprising a lower part comprising a wheel assembly for guidingthe container handling vehicle along a horizontal track system of theautomated storage and retrieval system, and a storage space arrangedcentrally within the lower part for accommodating a storage container ofthe automated storage and retrieval system.

The present invention also relates to a method of operating such anautomated storage and retrieval system.

BACKGROUND AND PRIOR ART

WO2016/120075A1, the contents of which are incorporated herein byreference, shows an example of an automated storage and retrieval systemof the type identified above. The disclosed container handling vehiclesare dimensioned so that they have a footprint, i.e. a contact areaagainst the track system, which has a horizontal extension that is equalto the horizontal extension of a grid cell. This allows the containerhandling vehicles to be operated simultaneously above neighbouring gridcells, liberating more space for the container handling vehicles totravel on the track system as compared to prior art systems.

Within the art, such a container handling vehicle, i.e. a containerhandling vehicle having a footprint with a horizontal extensioncorresponding to the horizontal extension of a single grid cell, issometimes referred to as a “single cell” container handling vehicle.

Another single cell container handling vehicle is disclosed inWO2015/193278A1, the contents of which are incorporated herein byreference.

The single cell design disclosed in WO2016/120075A1 and WO2015/193278A1reduces the space required for the container handling vehicles to travelon the track system, thus allowing more vehicles to operate on the tracksystem without interfering with each other.

There are situations where it may be beneficial that the containerhandling vehicles has a horizontal extension that is larger than asingle grid cell. For example, if the container handling vehicles areoperated under a battery replacement regime, in which a containerhandling vehicle is instructed to move to a battery replacement stationto have its onboard battery replaced when it nears depletion, it may beadvantageous, in order to facilitate battery replacement, to positionthe battery compartment or slot in a section of the vehicle body whichprotrudes beyond the footprint of the vehicle.

If the footprint of the container handling vehicle has a horizontalextension corresponding to the horizontal extension of a grid space, theprotruding battery slot will, when the vehicle is positioned above agrid cell, protrude into a neighbouring grid cell. This will preventother container handling vehicles from operating on the neighbouringgrid cell, thus limiting the space available for other containerhandling vehicles to operate on the track system.

In view of the above, it is desirable to provide an automated storageand retrieval system, a container handling vehicle for such a system,and a method for operating such a system, that solve or at leastmitigate the aforementioned problem related to the operation ofcontainer handling vehicles on the track system.

SUMMARY OF THE INVENTION

According to one aspect of the invention, the system is characterised inthat each container handling vehicle comprises:

-   -   a protruding section which extends horizontally beyond the        footprint of the container handling vehicle and, when the        container handling vehicle is positioned above a grid cell, into        a neighbouring grid cell; and    -   a recessed section arranged to accommodate the protruding        section of another container handling vehicle when it operates        over a neighbouring grid cell.

The recessed section is a region of clearance adapted to provideclearance for and/or temporally accommodate the protruding section ofanother container handling vehicle when it operates over a neighbouringgrid cell, thus allowing two container handling vehicle to operate orpass each other on neighbouring grid cells without contact between thecontainer handling vehicles being made.

According to another aspect of the invention, the container handlingvehicle is characterised in that it comprises a protruding sectionextending horizontally beyond the lower part and a recessed sectionarranged to accommodate the protruding section of another containerhandling vehicle when operating on the track system.

Another aspect of the invention relates to a method of operating anautomated storage and retrieval system, wherein a protruding section ofa first container handling vehicle is accommodated within a recessedsection of a second container handling vehicle when the first and secondcontainer handling vehicles operate on neighbouring grid cells.

Consequently, when operating on the track system, the recessed sectionof each container handling vehicle is capable of accommodating theprotruding sections of other container handling vehicles when they passover a neighbouring grid cell, thus allowing container handling vehiclesto travel along neighbouring rows of grid cells.

The recessed section may have a shape which is complementary to theshape of the protruding section. However, the recessed section may havea different shape than the protruding section as long as the recessedsection is capable of accommodating the protruding section of anothervehicle when it passes a neighbouring grid cell.

The recessed section may advantageously extend across the whole width orlength of the container handling vehicle in a direction which isorthogonal to the direction in which the protruding section extends,thus allowing two vehicles to completely pass each other on adjacentgrid cells. In other words, the recessed section forming the region ofclearance may extend from one side of the container handling vehicle.

The protruding section and the recessed section may be arranged at theupper part of the container handling vehicle.

The wheel assembly may comprise a first set of wheels for engaging withthe first set of tracks to guide movement of the container handlingvehicle in the first direction, and a second set of wheels for engagingwith the second set of tracks to guide movement of the containerhandling vehicle in the second direction.

The container handling vehicle may comprise a container-receivingstorage space for accommodating a storage container; a lifting devicearranged to transport a storage container vertically between a storageposition in a stack and a transport position in the storage space. Thelifting device may comprise a gripping device being configured toreleasably grip a storage container; and a lifting motor beingconfigured to raise and lower the gripping device relative to thestorage space.

The container-receiving storage space may be arranged centrally withinthe lower part of the container handling vehicle.

The protruding section may comprise at least one of: a rechargeablebattery; a battery slot for housing a replaceable battery; and a sensorfor establish the position of the vehicle on the track system orvis-à-vis other vehicles on the track system.

The wheel assembly may comprise wheels which are arranged around theperiphery of the storage space.

In the following, numerous specific details are introduced by way ofexample only to provide a thorough understanding of embodiments of theclaimed system, vehicle and method. One skilled in the relevant art,however, will recognize that these embodiments can be practiced withoutone or more of the specific details, or with other components, systems,etc. In other instances, well-known structures or operations are notshown, or are not described in detail, to avoid obscuring aspects of thedisclosed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Following drawings are appended to facilitate the understanding of theinvention.

FIG. 1 is a first side view of an embodiment of an automated storage andretrieval system according to the invention.

FIG. 2 is a second side view of the automated storage and retrievalsystem of FIG. 1, which second side view is orthogonal to the first sideview.

FIG. 3 is a top view of the automated storage and retrieval system ofFIGS. 1 and 2.

FIGS. 4 to 7 are perspective views of container handling vehiclesoperating over grid cells of the automated storage and retrieval systemaccording to FIG. 1.

FIG. 8 is a top view of a track system of the automated storage andretrieval system according to FIG. 1.

FIG. 9 is a top view of an alternative track system of an automatedstorage and retrieval system according to the invention.

FIG. 10 is a perspective view of a container handling vehicle accordingto one embodiment of the invention, in which view a top cover and a sidepanel of the vehicle are removed.

FIG. 11 is a side view of the container handling vehicle according toFIG. 10.

FIG. 12 is a cross-sectional view of the container handling vehicleaccording to FIG. 10.

FIG. 13 is a perspective view schematically showing an alternativeembodiment of a container handling vehicle according to the invention.

FIGS. 14A-C show an example of a charging and/or battery exchangestation in accordance with an embodiment. FIG. 14A shows a perspectiveview, FIG. 14B shows a side view along an X direction and FIG. 14C showsa side view along Y direction.

FIG. 15A-F show one possible battery exchange process in accordance withan embodiment.

FIG. 16A-D show one possible battery exchange process in accordance withan embodiment.

FIG. 17 shows the operation of the release mechanism in accordance withan embodiment.

FIG. 18 shows an example of a battery in accordance with an embodiment.

FIG. 19 shows a battery with support rails being inserted fully withinthe battery compartment in accordance with an embodiment.

In the drawings, like reference numerals have been used to indicate likeparts, elements or features unless otherwise explicitly stated orimplicitly understood from the context.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments of the invention will be discussed in moredetail by way of example only and with reference to the appendeddrawings. It should be understood, however, that the drawings are notintended to limit the invention to the subject-matter depicted in thedrawings.

An embodiment of a storage structure of an automated storage andretrieval system 1 according to the invention will now be discussed inmore detail with reference to FIGS. 1 to 8.

The storage structure comprises a framework 2 on which a plurality ofcontainer handling vehicles 3 a, 3 b are operated.

The framework 2 comprises a plurality of upright members 4 and aplurality of horizontal members 5, which are supported by the uprightmembers 4. The members 4, 5 may typically be made of metal, e.g.extruded aluminium profiles.

The framework 2 defines a three-dimensional storage grid comprisingstorage columns 7 arranged in rows, in which storage columns 7 storagecontainers 8, also known as bins, are stacked one on top of another toform stacks 9. Each storage container 8 may typically hold a pluralityof product items (not shown), and the product items within a storagecontainer 8 may be identical, or may be of different product typesdepending on the application of the system 1. The framework 2 guardsagainst horizontal movement of the stacks 9 of storage containers 8, andguides vertical movement of the containers 8, but does normally nototherwise support the storage containers 8 when stacked.

The horizontal members 5 comprise a rail or track system 10 arranged ina horizontal plane P above the storage columns 7 (see FIGS. 1 and 3), onwhich track system 10 the plurality of container handling vehicles 3 canmove laterally above the storage columns 7 to raise storage containers 8from and lower storage containers 8 into the storage columns 7, and alsoto transport the storage containers 8 above the storage columns 7.

The track system 10 comprises a first set of parallel rails or tracks 11arranged to guide movement of the container handling vehicles 3 in afirst direction X, and a second set of parallel rails or tracks 12arranged perpendicular to the first set of tracks 11 to guide movementof the container handling vehicles 3 in a second direction Y, which isperpendicular to the first direction X.

The track system 10 forms a grid structure or grid pattern 13 in thehorizontal plane P (see FIG. 3). The grid pattern 13 comprises aplurality of rectangular and uniform grid locations or grid cells 14(see FIG. 8), where each grid cell 14 comprises a grid opening 15 whichis delimited by a pair of tracks 11 a, 11 b of the first set of tracks11 and a pair of tracks 12 a, 12 b of the second set of tracks 12. InFIG. 8, the grid cell 14 is indicated by a box having dashed borders andthe grid opening 15 is indicated by a hatched area.

Consequently, tracks 11 a and 11 b form pairs of tracks definingparallel rows of grid cells running in the X direction, and tracks 12 aand 12 b form pairs of tracks defining parallel rows of grid cellsrunning in the Y direction.

Each grid cell 14 has a width W_(c) which is typically within theinterval of 30 to 150 cm, and a length L_(c) which is typically withinthe interval of 50 to 200 cm. Each grid opening 15 has a width W_(o) anda length L_(o) which is typically 2 to 10 cm less than the width W_(c),and the length L_(c), respectively, of the grid cell 14.

In the X and Y directions, neighbouring grid cells are arranged incontact with each other such that there is no space there-between.

One embodiment of a container handling vehicle 3 according to theinvention will now be discussed in more detail with additional referenceto FIGS. 10 to 12.

Each container handling vehicle 3 comprises a vehicle body 17 and awheel assembly 18 arranged in a lower section or part 17 a (see FIG. 12)of the vehicle body 17 to enable the lateral movement of the containerhandling vehicle 3, i.e. the movement of the vehicle 3 in the X and Ydirections (see FIG. 4).

The wheel assembly 18 comprises a first set of wheels 19, which isarranged to engage with a pair of tracks 11 a, 11 b of the first set oftracks 11, and a second set of wheels 20, which is arranged to engagewith a pair of tracks 12 a, 12 b of the second set of tracks 12 (seeFIG. 10). At least one of the set of wheels 19, 20 can be lifted andlowered, so that the first set of wheels 19 and/or the second set ofwheels 20 can be brought to engage with the respective set of tracks 11,12 at any one time.

Each set of wheels 19, 20 comprises four wheels 19 a, 19 b, 19 c, 19 d;20 a, 20 b, 20 c, 20 d arranged along the sides of the vehicle (seeFIGS. 4 and 7). Wheels 19 a and 19 b are arranged in a first verticalplane, and wheels 19 c and 19 d are arranged in a second vertical planewhich is parallel to the first vertical plane and arranged at a distancefrom the first vertical plane which corresponds to the distance betweenrails 11 a and 11 b (see FIG. 8). Wheels 20 a and 20 b are arranged in athird vertical plane, which is orthogonal to the vertical planes inwhich wheels 19 a-19 d are arranged, and wheels 20 c and 20 d arearranged in a fourth vertical plane which is parallel to the thirdvertical plane and arranged at a distance from the third vertical planewhich corresponds to the distance between rails 12 a and 12 b.

At least one of the wheels in each set 19, 20 is motorized in order topropel the vehicle 3 along the track system 10. Advantageously, the atleast one motorized wheel in each set comprises a hub motor, i.e. anelectric motor that is coupled to, or incorporated into, the hub of awheel and drives the wheel directly. An example of a container handlingvehicle with such a motor is disclosed in WO2016/120075A1, the contentsof which are incorporated herein by reference.

Each container handling vehicle 3 comprises a storage compartment orstorage space 24 arranged centrally within the lower part 7 a of thevehicle body 17 for receiving and holding a storage container 8 whentransporting the storage container 8 across the track system 10. Thestorage space 24 is arranged within the vehicle body 17 and can beaccessed from below, i.e. from an opening (not shown) at the bottom ofthe container handling vehicle 3.

Each container handling vehicle 3 also comprises a lifting device 21(see FIG. 10) for vertical transportation of a storage container 8, e.g.lifting a storage container 8 from a storage column 7 and bringing itinto the storage space 24, and also for lowering a storage container 8from the storage space 24 into a storage column 7. The lifting device 21comprises a latching or gripping device 22 which is arranged toreleasably engage with a storage container 8. The lifting device alsocomprises a lifting motor 23 for lowering and raising the grippingdevice 22 so that the position of the gripping device 22 with respect tothe vehicle body 17 can be adjusted in a third direction Z, which isorthogonal to the first direction X and the second direction Y (see alsoFIG. 4).

Conventionally, and also for the purpose of this application, Z=1identifies the uppermost layer of the storage grid, i.e. the layerimmediately below the track system 10, Z=2 identifies the second layerbelow the track system 10, Z=3 identifies the third layer etc. Thecontainer handling vehicles 3 can be said to travel in layer Z=0.Consequently, each storage column can be identified by its X and Ycoordinates, and each storage position in the storage grid can beidentified by its X, Y and Z coordinates.

The lifting motor 23 is arranged in a second, upper part or section 17 bof the vehicle body 17 (see FIG. 12), which upper part 17 b is locatedabove the lower part 17 a.

When a storage container 8 stored in the storage grid is to be accessed,one of the container handling vehicles 3 is instructed to retrieve thetarget storage container 8 from its position in the storage grid and totransport the target storage container 8 to an access station (notshown) where it can be access from outside of the storage grid ortransferred out of the storage grid. This operation involves moving thecontainer handling vehicle 3 to the grid cell 14 above the storagecolumn 7 in which the target storage container is positioned andretrieving the storage container from the storage column 7 using thecontainer handling vehicle's lifting device 21. This step involves usingthe lifting device 21 to lift the storage container from the storagecolumn 7 through the grid opening 15 of the grid cell 14 and into thestorage space 24 of the vehicle 3.

If the target storage container is located deep within a stack 9, i.e.with one or a plurality of other storage containers positioned above thetarget storage container, the operation also involves temporarily movingthe above-positioned storage containers prior to lifting the targetstorage container from the storage column 7. This step, which issometimes referred to as “digging” within the art, may be performed withthe same container handling vehicle that is subsequently used fortransporting the target storage container to the access station, or withone or a plurality of other cooperating container handling vehicles.Alternatively, or in addition, the automated storage and retrievalsystem may have container handling vehicles specifically dedicated tothe task of temporarily removing storage containers from a storagecolumn. Once the target storage container has been removed from thestorage column, the temporarily removed storage containers can berepositioned into the original storage column. However, the removedstorage containers may alternatively be relocated to other storagecolumns.

Once the target storage container has been brought into the storagespace 24 of the container handling vehicle 3, the vehicle transports thestorage container to the access station where it is unloaded. The accessstation may typically comprise a grid location at the periphery of thestorage grid where the storage container can be accessed manually ortransported further using a suitable conveyor system.

When a storage container 8 is to be stored in the storage grid, one ofthe container handling vehicles 3 is instructed to pick up the storagecontainer from a pick-up station (not shown), which may also double asan access station, and transport it to a grid cell above the storagecolumn 7 where it is to be stored. After any storage containerspositioned at or above the target position within the storage columnstack have been removed, the container handling vehicle 3 positions thestorage container at the desired position. The removed storagecontainers may then be lowered back into the storage column 7, orrelocated to other storage columns within the storage grid.

For monitoring and controlling the automated storage and retrievalsystem so that a desired storage container can be delivered to thedesired location at the desired time without the container handlingvehicles 3 colliding with each other, the automated storage andretrieval system comprises a control system (not shown), which typicallyis computerised and comprises a database for monitoring and controllinge.g. the location of the respective storage containers 8 within thestorage grid, the content of each storage container 8 and the movementof the container handling vehicles 3.

The container handling vehicles 3 typically communicates with thecontrol system via wireless communication means, e.g. via a WLANoperating under an IEEE 802.11 (WiFi) standard and/or utilising a mobiletelecommunication technology such as 4G or higher.

Each container handling vehicle 3 comprises a battery 25 which providespower to onboard equipment, including the motorised wheels, the liftingmotor and onboard control and communications systems.

Each container handling vehicle 3 has a footprint, i.e. a contact areaagainst the track system 10, which has a horizontal extension which isequal to or less than the horizontal extension of a grid cell 14. Inother words, when the vehicle 3 is positioned above a grid cell 14, e.g.for lifting a storage container from or lowering a container into astorage column 7, the footprint of the vehicle 3 will not extend beyondthe grid cell into a neighbouring grid cell.

The wheels 19 a-19 d, 20 a-20 d are arranged around the periphery of thestorage space 24, and the footprint 14 of the vehicle 3 is larger thanthe storage space 24 only enough to accommodate the wheels 19 a-19 d, 20a-20 d. In this way, the footprint 14 of the vehicle 3 takes up theminimum possible amount of space in the X-Y plane. Since the storagespace 24 is positioned between the pair of wheels 19 a-19 d, 20 a-20 don each side of the vehicle 3, the centre of gravity of the vehicle 3will be located within the footprint 14 also when a storage bin israised into the storage space 24.

Further, the vehicle 3 comprises generally vertical side walls 26 a-26 d(see FIGS. 4, 6 and 7), which are co-planar to the vertical planes inwhich the wheels 19 a-19 d; 20 a-20 d are arranged. Consequently, thelower part of the container handling vehicle 3 has a generally cuboidshape.

However, the upper part 17 b of the vehicle 3 has a protruding section27 which extends horizontally in the X direction beyond the otherwisegenerally vertical side wall 26 c (e.g. see FIGS. 2 and 4). This section27 houses the battery 25 of the vehicle 3 (see FIG. 7). Positioning thebattery in this manner is advantageous since it allows charging orbattery exchange stations easy access to the battery for charging orbattery replacement. In particular, if a battery exchange scheme isused, in which case the protruding section 27 comprises a batterycompartment or slot 28 (e.g. see FIG. 12), the protruding character ofsection 27 provides advantageous guiding for the battery 25 duringbattery exchange operation.

The protruding section 27 also allows larger batteries to be mounted inthe vehicle and may also be beneficial when operating the vehicles as atrain of vehicles, e.g. as is disclosed in the international patentapplication PCT/EP2016/077300.

Alternatively, or in addition, the protruding section 27 may holddown-looking sensors, which may be used to establish the position of thevehicle on the track system 10, e.g. the alignment of the vehiclevis-à-vis a grid cell 14, or to establish the position of the vehiclevis-à-vis other vehicles on the track system 10, e.g. when operating thevehicles as a train of vehicles.

When the vehicle 3 is positioned above a grid cell 14, e.g. to access acontainer 8 in the storage column 7 located vertically below the gridcell 14, the protruding section 27 will extend over a neighbouring gridcell. In other words, even though the vehicle 3 has a contact areaagainst the rail system 10 which does not extend beyond the horizontalextent of one grid cell 14, the vehicle has a vertical projection whichoccupies more than one grid cell.

Normally this would prevent a second vehicle from travelling over theneighbouring grid cell, i.e. the grid cell into which the protrudingsection 27 of the first vehicle extends. This could be a problem sinceit could reduce the overall capacity of the automated storage andretrieval system.

However, the container handling vehicle 3 comprises a recessed section29 which is arranged in the upper part 17 b opposite to the protrudingsection 27. In other words, the protruding section 27 and the recessedsection 29 are arranged at opposite sides of the container handlingvehicle 3. The recessed section 29 is capable of accommodating theprotruding sections 27 of other vehicles when they pass over aneighbouring grid cell. In particular, the recessed section 29 has ashape which is complementary to the shape of the protruding section 27and extends across the whole width of the container handling vehicle 3in the Y direction, thus allowing vehicles 3 to pass each other overadjacent grid cells.

This is illustrated in FIGS. 4 to 6, which show a first vehicle 3 amoving in to operate over a grid cell while a second vehicle 3 b ispositioned over a neighbouring grid cell while the protruding section 27a of the first vehicle 3 a is accommodated in the recessed section 29 bof the second vehicle 3 b.

In the disclosed embodiment, the protruding section 27 of each containerhandling vehicle 3 extends in the X direction and the recessed section29 extends across the whole width of the vehicle 3 in the Y direction.However, it is understood that the protruding section may alternativelyextend in the Y direction and the recessed section extend across thewhole width of the vehicle in the X direction.

Each container handling vehicle may alternatively have two protrudingsections 27′, 27″ extending in two orthogonal directions and twoopposite, complementary recessed sections 29′, 29″, as is schematicallyillustrated by the container handling vehicle shown in FIG. 13. Thisconfiguration will also allow two vehicles to operate over neighbouringgrid cells without the protruding sections 27′ and 27″ hindering themovement of other vehicles on the track system.

In the track system 10 shown in FIG. 8, each horizontal member making upthe tracks comprises two tracks. Consequently, each horizontal member iscapable of accommodating two wheels in parallel. In such a track system,the borders between neighbouring grid cells run along the centre-line ofthe horizontal members, as is indicated in FIG. 8.

FIG. 9 shows an alternative rail or track system 16 which is made up byelongated members each forming a single track, i.e. a track configuredto accommodate only one wheel. In such a track system the bordersbetween neighbouring grid cells run midway between neighbouringelongated members forming the single tracks.

In FIG. 9, grid cell 14 comprises a grid opening 15. To the left (West)of grid cell 14, there is an adjacent grid cell 14W comprising a gridopening 15W. Likewise, to the right (East) of grid cell 14, there is anadjacent grid cell 14E comprising a grid opening 15E. Also, below gridcell 14 (South), there is an adjacent grid cell 14S comprising a gridopening 15S, and above grid cell 14 (North), there is an adjacent gridcell 14N comprising a grid opening 15N.

In FIG. 9, a footprint 30 of a container handling vehicle isschematically illustrated. In this embodiment the footprint 30 isdefined by the horizontal extension of the wheels of the vehicle. As isevident from the figure, the footprint 30 has a horizontal extent whichis less than the horizontal extent of a grid cell.

In FIG. 9, a footprint 30′ of a container handling vehicle according toan alternative embodiment is also schematically illustrated. In thiscase the lower part of the vehicle extends beyond the wheels and thefootprint 30′ has a horizontal extension which is equal to than thehorizontal extension of a grid cell.

As previously mentioned, the protruding section 27 may comprise abattery compartment or slot 28 for a rechargeable or a replaceablebattery 25. In the following, such an embodiment and an associatedbattery exchange scheme will be discussed in more detail with referenceto FIGS. 14 to 19.

An example of a charging and/or battery exchange station 40, hereinafterreferred to as a charging station, is shown in FIG. 14, both in aperspective view (FIG. 14 A) and in side views along X direction (FIG.14 B) and along Y direction (FIG. 14 C).

The charging station 40 is mounted on a charging station base plate 41,which is fixed (directly or indirectly) to neighbouring rails 11 a, 11b,12 a,12 b of the track system above a grid column at or near theperimeter of the framework structure. The particular grid columncontaining the charging station 40 will hereinafter be referred to as acharging station cell.

The charging station 40 shown comprises a vertical charging stationcolumn 42 fixed at a lower end 42 a to the based plate 41. A chargingsocket 45 is arranged at or near an upper end 42 b of the column 42,i.e. opposite to the lower end 42 a, and electrically connected to apower supply 44, possibly via a power transformer transforming thecharging power to the desired power level.

The charging socket 45 is further configured to receive a charging plug46 of the battery 25 installed on each vehicle 3 (see. FIG. 18), therebyallowing flow of electric power when the charging plug 46 iselectrically coupled to the charging socket 45.

In a preferred configuration, the charging socket 45 is resilientlyattached to the charging station 42, for example such that the positionof the charging socket 45 is fixed in an upper (unloaded) position whenno external force act on the charging socket 45 and in a lower (loaded)position when the charging socket is exposed to the weight of theelectrically connected battery 25.

The charging socket 45 and the charging plug 46 may of course beinterchanged.

In general, any kind of disconnectable electrical connections betweenthe charging station 40 and the battery 25 is possible.

An automated storage and retrieval system as described herein maycomprise a plurality of such charging stations 40, typically arrangedalong the perimeter of the track system. However, one or more chargingstations 40 may alternatively or additionally be placed further into thetrack system and/or fully outside of the track system. In the latterconfiguration, the charging station(s) 40 should be connected to thetrack system by additional rails in order to allow the vehicles 3 totravel to their respective charging station 40.

One possible battery exchange process will now be described withparticular reference to FIGS. 15 to 17.

A vehicle 3, having transferred its discharged, or partly discharged,main battery from its battery compartment or slot within a battery cover31 to a first charging station for charging, approaches a secondcharging station 40 containing a charged, or partly charged, mainbattery 25 (see FIG. 15A and FIG. 16C).

To allow the vehicle to enter the charging station storage cell, thefirst set of wheels 19 a-d should contact the underlying track system(see FIG. 15 A-D) and the second set of wheels 20 a-d closest to thecharging station 30 should be sufficiently high above the track systemin order not to interfere with the tracks along the Y direction.

When wheels 20 a and 20 b of the second set of have entered the chargingstation storage cell, and prior to reaching the horizontal positionwhere the charging station 40 is contacting the approaching vehicle 3,the vehicle 3 is lowered towards the track system. The lowering isperformed to allow correct alignments with the main battery 25 duringthe battery exchange process since the weight of the battery 25 forcesthe charging socket 45 down to its lower (loaded) position as explainedabove. A lowering of the vehicle 3 also increases the overall stabilityof the exchange procedure. Typical vertical displacement of the vehicle3 is 5-15 mm, for example 10 mm.

The charging station 40 should thus be configured such that the heightof the main battery 25 under charge, relative to the track system, isapproximately equal to the corresponding height of the batterycompartment on the vehicle 3 when the vehicle 3 is in a loweredposition.

To allow movements of the vehicle 3 being void of a main battery 25, anauxiliary battery may be installed, for example in the same or similarway as disclosed in the patent publication WO 2015/104263 A1, thecontents of which are incorporated herein by reference. Other solutionsmay also be envisaged, for example use of external power sources such aslive rails, manual interference, etc.

Alternative embodiments in which either the charging station 40 or thevehicle 3 or a combination of both contain a plurality of batteries,thereby avoiding the need of vehicle movements between charging stations40 during battery exchange. A multi-battery charging station applicablefor the above mentioned storage system 1 is disclosed in WO 2017/220627A1, the contents of which are incorporated herein by reference.

The available charged battery 25 on the second charging station 40 ismounted onto a battery support 43, which in the example shown in FIGS.14-16 is in form of two guiding pins 43 a, 43 b extending laterally intothe track system from each side of the charging station column's 42upper end 42 b.

When the vehicle 3 is contacting the charging station 40, a releasemechanism 50 (see FIG. 17) is activated, allowing the battery cover 31to be tilted around a rotational axis.

The release mechanism 50 comprises a pivot arm 51 arranged at both sidesof the opening of the battery compartment into which the battery 25 isto be inserted.

Further, each of the protruding ends of the guiding pins 43 a,43 b(constituting the battery support 43) displays a tapered section 52 (seeFIGS. 14A and 14C). Upon contact between the pivot arm 51 and theguiding pins 43, a pivot arm contact element 51 a of each pivot arm 51is pushed towards the tapered section 52, thereby enforcing an upwarddirected pivoting movement of the pivot arm 51 (see FIG. 15A, FIG. 16Dand FIG. 17). This pivot movements releases a security lock 51 b (seeFIGS. 15 and 19) allowing the above mentioned tilt of the battery cover31.

The operation of the release mechanism 50 is illustrated in each of thesequence drawings in FIG. 15 and in FIG. 17. To increase clarity,enlarged area drawings of the release mechanism 50 is added in FIG. 15A-C and FIG. 15 F. The enlarged area drawings clearly show theactivation of the pivot arm movement upon contact with the taperedsection 52 moving the security lock 51 b away from the battery cover 27and the subsequent entry of the battery 25.

When the guiding pins 43 with the attached battery 28 has entered acertain distance into the battery compartment 27 a (see FIGS. 15 B andC), the guiding pins 43 releases a battery lock 27 b, 27 c that allowsfurther entry until the battery 25 is fully in its end position withinthe battery compartment.

In FIG. 19, the battery lock 27 b,c comprises a battery lock activator27 b in the form of a wheel and one or more blocking teeth 27 cextending from the inner walls of the battery cover and into the batterycompartment. When the tapered ends 52 of the guiding pins 43 a,bcontacts the battery lock activator 27 b, the battery cover 27 is tiltedupwards, thereby displacing the one or more teeth 27 c such that thebattery 25 and the guiding pins 43 a,b may continue the movement deeperinto the battery compartment.

In this end position, and before retraction of the vehicle 3, thebattery 25 can be electrically connected two both the charging station40 and i.e. the drive motors for the wheels 19 a-d,20 a-d.

When the battery is in its end position inside the battery compartmentand in electrical contact with the corresponding electrical connector ofthe vehicle 3, the battery compartment tilts back to its initialposition such that the teeth 27 c physically locks or holds the battery25 within the battery compartment. As an example, the teeth 27 c mayenter dedicated recesses 49 a within support rails 49 arranged at bothsides of the battery 28 (see FIG. 17).

The battery lock 27 b,c may be any physical hindrance within the batterycompartment. As an alternative to the above-mentioned teeth 27 c, thebattery lock may comprise one or more protruding wedges that the battery25 may surpass in one direction, but not in the other. In thisconfiguration, the wedge shape would act as the battery lock activator27 b.

When the battery 25 is in its end position and successfully locked intothe battery compartment by the battery lock 27 b,c, the second set ofwheels 20 a-d of the vehicle 3 is lifted from the track system(typically between 5-15 mm), thereby lifting the overall height of thevehicle 3. This operation causes the battery 25 to be released from thebattery support 43, for example from dedicated pockets or tracks withinthe first and second guiding pins 43 a,b (see FIG. 14A).

Since now the battery lock 27 b,c is locking the battery 25 into thebattery compartment, and the battery 25 has been lifted free from thebattery support 43, a retraction of the vehicle 3 out of the chargingstation storage cell leaves the battery 25 electrically connected to thevehicle 3.

In addition to allowing successful exchange of battery, the blocking ofthe battery 28 into the battery compartment 27 a has the advantage thatthe battery 28 cannot be unintentionally displaced within the batterycover 27 during operation.

When the control system has sent an instruction to the vehicle 3 toplace its battery 28 into a charging station 40 for charge, the stepsfor transferring the battery 28 from the vehicle 3 to the chargingstation 40 are essentially equal or similar to the opposite sequence anddirection of the above-mentioned steps of transferring the battery 28from the charging station 40 to the vehicle 3.

Hence, the vehicle 3 is first raised to both allow the vehicle to enterthe charging station storage cell without interference of the second setof wheels 20 with the tracks 11 in the second direction (Y) and to alignthe operative battery 25 with the charging plug 45 of the chargingstation 40. As mentioned above, the charging plug 45 is in the exemplaryconfiguration of FIGS. 14-17 in an upper, unloaded position.

During the approach of the vehicle 3 towards the charging station 40,the wedged ends 52 of the first and second guiding pins 43 a,b firstactivate the tilt of the battery compartment via the release mechanism51, then activate the battery lock 27 b,c causing the battery cover totilt upwards, thereby removing the blocking teeth 27 c from thecorresponding recesses 49 a in the support rail 49.

By lowering the vehicle 3 towards the track system, the support rails 49of the battery 28 mesh with the battery support 43. A subsequentretraction of the vehicle 3 would thus leave the battery in the desiredcharging position on the charging station 40.

To allow larger batteries within the vehicle 3, both the battery coverand the optional release mechanism 50 may be arranged so that theyprotrude horizontally in the X direction beyond the otherwise generallyvertical side walls 26 c and 26 d. In this way, the overall capacity ofeach vehicle 3 in the system 1 may be increased significantly withoutnecessitating making the tracks 11,12 wider.

In case there is a need of manual interference for removing the batteryfrom the battery compartment, for example due to general maintenance oraccidental battery jamming, a configuration with a protruding releasemechanism 50 has an additional advantage in that it allows easy manualunlocking of the battery. That is, the protruding arrangement allows forexertion of sufficient manual force on the release mechanism 50, anoperation that would be difficult if for example the release mechanism50 was arranged deep within the battery cover 27.

The protruding configuration described above is also beneficial forensuring early engagement in the charging station 40.

An example of a battery 25 is shown in perspective in FIG. 18. One oftwo support rails 49 is shown protruding from a side wall of the battery25. And identical support rail is protruding from the opposite sidewall. The purpose of the support rails 49 is to both ensure a stablesupport of the battery 25 on the battery support/guiding pins 43 and toensure an accurate guiding of the battery 25 into and out of the batterycompartment during exchange. FIG. 19 shows the battery 25 with supportrails 49 being inserted fully within the battery compartment. In theparticular configuration shown in FIG. 19, the battery 25 isapproximately half the maximum allowable volume of a battery.

In the preceding description, various aspects of an automated storageand retrieval system according to the invention have been described withreference to the illustrative embodiment. However, this description isnot intended to be construed in a limiting sense. Various modificationsand variations of the illustrative embodiment, as well as otherembodiments of the system, which are apparent to persons skilled in theart, are deemed to lie within the scope of the present invention asdefined by the following claims.

The invention claimed is:
 1. An automated storage and retrieval systemcomprising: a track system comprising a first set of parallel tracksarranged in a horizontal plane and extending in a first direction, and asecond set of parallel tracks arranged in the horizontal plane andextending in a second direction which is orthogonal to the firstdirection, which first and second sets of tracks form a grid pattern inthe horizontal plane comprising a plurality of adjacent grid cells, eachcomprising a grid opening defined by a pair of adjacent tracks of thefirst set of tracks and a pair of adjacent tracks of the second set oftracks; a plurality of stacks of storage containers arranged in storagecolumns located beneath the track system, wherein each storage column islocated vertically below a grid opening; a plurality of containerhandling vehicles for lifting and moving storage containers stacked inthe stacks, the container handling vehicles being configured to movelaterally on the track system above the storage columns to access thestorage containers via the grid openings, wherein each of the pluralityof container handling vehicles comprises: a wheel assembly for guidingthe container handling vehicle along the track system; wherein thecontainer handling vehicle has a footprint with a horizontal extentwhich is equal to or less than the horizontal extent of a grid cell,wherein each container handling vehicle comprises: a protruding sectionwhich extends horizontally beyond the footprint of the containerhandling vehicle and, when the container handling vehicle is positionedabove a grid cell, into a neighbouring grid cell; and a recessed sectionarranged to accommodate the protruding sections of another containerhandling vehicle when operating over a neighbouring grid cell.
 2. Thesystem according to claim 1, wherein the recessed section has a shapewhich is a counterpart to the shape of the protruding section.
 3. Thesystem according to claim 1, wherein the recessed section extends acrossthe whole width or length of the container handling vehicle in adirection which is orthogonal to the direction in which the protrudingsection extends.
 4. The system according to claim 1, wherein theprotruding section comprises at least one of: a rechargeable battery; abattery slot for housing a replaceable battery; and a downward-lookingsensor.
 5. The system according to claim 1, wherein the protrudingsection and the recessed section are arranged at an upper part of thecontainer handling vehicle.
 6. The system according to claim 1, whereinthe wheel assembly comprising a first set of wheels for engaging withthe first set of tracks to guide movement of the container handlingvehicle in the first direction, and a second set of wheels for engagingwith the second set of tracks to guide movement of the containerhandling vehicle in the second direction.
 7. The system according toclaim 1, wherein the container handling vehicle comprises: acontainer-receiving storage space for accommodating a storage container;a lifting device arranged to transport a storage container verticallybetween a storage position in a stack and a transport position in thestorage space, the lifting device comprising: a gripping device beingconfigured to releasably grip a storage container; and a lifting motorbeing configured to raise and lower the gripping device relative to thestorage space.
 8. The system according to claim 7, wherein thecontainer-receiving storage space is arranged centrally within a lowerpart of the container handling vehicle.
 9. A container handling vehiclefor an automated storage and retrieval system, the container handlingvehicle comprising a lower part comprising a wheel assembly for guidingthe container handling vehicle along a horizontal track system of theautomated storage and retrieval system, and a storage space arrangedcentrally within the lower part for accommodating a storage container ofthe automated storage and retrieval system, wherein the containerhandling vehicle comprises a protruding section extending horizontallybeyond the lower part and a recessed section arranged to accommodate theprotruding section of another container handling vehicle (3 b) whenoperating on the track system.
 10. The container handling vehicleaccording to claim 9, wherein the protruding section and the recessedsection are arranged at an upper part of the container handling vehicleabove the lower part.
 11. The container handling vehicle according toclaim 9, wherein the recessed section has a shape which is a counterpartto the shape of the protruding.
 12. The container handling vehicleaccording to claim 9, wherein the protruding section and the recessedsection are arranged at opposite sides of the container handlingvehicle.
 13. The container handling vehicle according to claim 9,wherein the protruding section comprises at least one of: a rechargeablebattery; a battery slot for housing a replaceable battery; and a sensorfor establishing the position of the vehicle on the track system orvis-à-vis other vehicles on the track system.
 14. The container handlingvehicle according to claim 9, wherein the wheel assembly compriseswheels which are arranged around the periphery of the storage space. 15.A method of operating an automated storage and retrieval system, whereinthe automated storage and retrieval system comprises: a track systemcomprising a first set of parallel tracks arranged in a horizontal planeand extending in a first direction, and a second set of parallel tracksarranged in the horizontal plane and extending in a second directionwhich is orthogonal to the first direction, which first and second setsof tracks form a grid pattern in the horizontal plane comprising aplurality of adjacent grid cells, each comprising a grid opening definedby a pair of adjacent tracks of the first set of tracks and a pair ofadjacent tracks of the second set of tracks; a plurality of stacks ofstorage containers arranged in storage columns located beneath the tracksystem, wherein each storage column is located vertically below a gridopening; a plurality of container handling vehicles for lifting andmoving storage containers stacked in the stacks, the container handlingvehicles being configured to move laterally on the track system abovethe storage columns to access the storage containers via the gridopenings, wherein each of the plurality of container handling vehiclescomprises: a wheel assembly for guiding the container handling vehiclealong the track system; wherein the container handling vehicle has afootprint with a horizontal extent which is equal to or less than thehorizontal extent of a grid cell, wherein each container handlingvehicle comprises: a protruding section which extends horizontallybeyond the footprint of the container handling vehicle and, when thecontainer handling vehicle is positioned above a grid cell, into aneighbouring grid cell; and a recessed section arranged to accommodatethe protruding sections of another container handling vehicle whenoperating over a neighbouring grid cell, and wherein a protrudingsection of a first container handling vehicle is accommodated within arecessed section of a second container handling vehicle when the firstand second container handling vehicles operate on neighbouring gridcells.